The present invention relates to the field of pharmaceutical chemistry and relates to intermediates and processes for preparing benzothiophenes.
Compounds of formula I ##STR1## wherein R is --COR.sup.3 or --SO.sub.2 R.sup.3, X is chloro, bromo, or SO.sub.2 R.sup.3, and R.sup.3 is C.sub.1 -C.sub.4 alkyl, trifluoromethyl, trichloromethyl, phenyl, p-tolyl, p-anisyl, or mono- or di(halo or nitro)phenyl may be prepared as described U.S. Pat. No. 4,358,593, the disclosure of which is herein incorporated by reference. That patent teaches an acylation reaction in which a compound of formula III ##STR2## wherein R is, in both instances, a hydroxy protecting group, is reacted with a compound of formula IV ##STR3## wherein R.sup.4 is chloro, bromo, iodo, or an acyl activating group, under Friedel-Crafts acylation conditions, to provide a compound of formula I. If a compound of formula I where R is hydrogen is desired, this process requires two separate reactions and purifications- one for the acylation reaction, described above, and one for the deprotection reaction at the 4' and 6 positions.
Thus, a more efficient and less expensive process for preparing compounds of formula I would be a significant contribution to the art.